1. Field of the Invention
The present invention relates to coating compositions capable of affording coated surfaces superior in surface hardness, abrasion resistance, flexibility, dyeability and durability.
2. Description of Prior Art
Heretofore, attempts to coat articles for improving characteristics, especially surface characteristics and cosmetic quality, of the articles have often been made. Particularly, as to articles which are easily scratched, various coatings have been tried for rendering those articles difficult to be scratched. Also as to articles which are difficult to be scratched, such as glasses, ceramics and metals, the coating method is an important means for coloring them easily without impairing their characteristic that they are difficult to be scratched. In the former case, many proposals have so far been made with respect to plastic articles. For example, a silicic coating material (see U.S. Pat. Nos. 3,451,838 and 3,894,881) and a coating material of silicon compounds containing silica particles (see U.S. Pat. No. 3,986,997) have been proposed, but these materials are poor in flexibility and of more importance is that they lack sufficient dyeability. Vinyl copolymers having an alkoxysilyl group have also been proposed (see U.S. Pat. Nos. 3,427,187 and 3,467,634 and Japanese Patent Laid Open No. 43242/1979), but with these copolymers it is impossible to expect a high hardness although they are superior in adhesion and rust-preventive property for specific substances. For reference, the Japanese Patent Laid Open No. 43242/1979 has the following claim:
"A resin coposition of rust-preventive paint, comprising (A) 5 to 50 parts by weight of an acrylic copolymer, said acrylic copolymer comprising 0.1 to 50% by weight of at least one silicone monomer represented by the general formula ##STR1## wherein R.sub.1 is a hydrogen atom or methyl, R.sub.2, R.sub.3 and R.sub.4 are each an alkyl group having 1 to 4 carbon atoms, n is an integer of 1 to 12 and m is an integer of 1 to 10, 5 to 50% by weight of styrene and not more than 94.9% by weight of vinyl monomer, and (B) 50 to 95 parts by weight of an acrylic copolymer containing 5 to 50% by weight of styrene." PA1 A. vinyl polymers having a group represented by the general formula R.sup.1.sub.m (R.sup.2 O).sub.3-m Si- wherein R.sup.1 is methyl or ethyl, R.sup.2 is an alkyl, alkoxyalkyl or acyl group having not more than 4 carbon atoms, with silicon attached to the polymer by Si-C bond, and m is 0, 1 or 2, and PA1 B. fine particles of silica having an average diameter of particles in the range of about 1 to about 200 nm. PA1 (1) Unsaturated vinyl monomers containing a group represented by the above-mentioned general formula are homopolymerized or copolymerized with other vinyl monomers. (Vinyl monomers as referred to herein mean monomers having a polymerizable double bond such as vinyl, substituted vinyl or allyl.) PA1 (2) Vinyl polymers having a reactive functional group are reacted with reactive compounds having a group represented by the above-mentioned general formula.
Furthermore, as a dyeable coating material having a high hardness, there has been proposed a cured product of silane hydrolysate and fine particles of silica using a catalyst of aluminum compounds (see U.S. Pat. No. 4,211,823), but its insufficient stability leads to an increase of cost.